Arming device



J. RABnwowv ARMING DEVICE June 14, 1955 2 Sheets-SheetI l Filed Deo. so, 1944 INVENTOR JB RAB/0W 3a 20h 4e 201; 37 0b ATTORNEY June 14, 1955 .1. RABlNow 2,710,573

ARMING DEVICE Filed Dec. so, 1944 2 sheets-sheet 2 ATTORNEY ilnited tates Patent @dass 2,710,573 Patented June 14, i955 ARMNG DEVICE Jacob Rabinow, Washington, D. C., assigner to the United States of America as represented by the Secretary of the Navy Application December 36, 1944, Serial No. 576,717

13 Claims. (Cl. VIGZ-40.2)

(Granted under Ttie 35, U. S. Code.(1952), sec. 266) This invention relates to arming devices, such as those used with electrically operated projectile fuzes, and more particularly to a novel inertia operated switch having means for moving a powder train interrupter to an operative position.

An object of my invention is to provide a novel switching device operated by inertia and having means for moving a powder train interrupter to an operative position.

Another' object of my invention is to provide a novel inertia operated switching device which operates upon sustained acceleration of a projectile in flight to close an arming circuit, and upon substantial cessation of the acceleration to close a second arming circuit and to move a powder train interruptor to operative position.

A further object of my invention is to provide a switching device as described above, which also includes a third Aswitch for causing self-destruction of the projectile.

A further object of the invention is to provide an arming device particularly adapted for use with electrically operated projectile fuzes employing an electronic tube and in which it is important to delay the arming of the device vuntil the projectile has traveled a safe distance from the operator and until the electronic tube has become suiiiciently heated. Premature explosions resulting from the shock of tiring or from rough handling are thus avoided.

Another object of the invention is to provide a device of the character described which is simple in construction and positive in operation and is adaptable to large scale manufacture. j

These and other objects of the invention will be apparent from the following description and the accompanying drawings, in which:

Fig. l is an exploded perspective view of one embodiment of the invention;

Fig. 2 is a perspective view of the assembled device shown' in Fig. l, with the parts -in their unarmed positions;

Fig. 3 is a right hand elevational view of the device shown in Fig. 2;

Fig. 4 is'a plan view of the device shown in Fig. 2; Figs. 5, 6 and 7 are cross-sectional views taken on lines S-5, 6 6 and 7-7, respectively, of Fig. 4;

Fig. 8 is an elevational View similar to Fig. 3 but showing the parts in their armed positions, and

Fig. 9 is a view similar to Fig. 5 but showing the parts in their armed positions.

ln the drawings, an insulating disc 2t) is fastened to block 21, which may be of plastic or other suitable insulating material, by means of screws 20a. A plurality of electrically conducting plugs Ztlb project downwardly from the lower surface of disc 20 for electrically connecting the device to other parts ofthe fuze. Block 21 has a centrally located passage 21a which is positioned in alignment with an axial opening 2lb in the disc 20 and is adapted to contain a squib (not shown). -A slide 23 has a downwardly extending tube 23a mounted in a hole 22 near one end of the slide, and is disposed on block 21. On the other end of slide 23, a strip of electrically conducting material 24 formed with a shoulder 24e is mounted transversely on the under surface of the slide and insulated from the slide by insulation 24a so as to close a circuit between a pair of resilient contacts Zlib mounted on the block 21, as will be explained presently. The slide has two downwardly projecting arms 25 and 25, the purpose of which will be explained presently. The arms 25 and 26 ride in a cutaway portion 25a in one side of the block 21, while a downwardly projecting wall 26a on the slide rides in a cutaway portion 26b on the other side of the block 21.

A pair of metal frame members 27 and 28 are attached to block 21 by means of screws or other suitable means. A shaft 29 is rotatably mounted in frame members 2'7 and 2S and carries a gear wheel 30 near the end adjacent frame member 27. Near the other end of the shaft 29 is mounted a notched wheel 31 which carries Weight 32 near its periphery. The end of shaft 29 which extends through frame member 28 is partly cut away leaving a semi-circular portion 33 for a purpose to be explained presently.

A second shaft 34 supported by block 21 and frame member 28 carries an escapement weight 35 on which are mounted pins 36 and 37 so as to engage the notches of wheel 31 to constitute an escapement.

A third shaft 3S projects from the outer surface of frame member 28 to support a rotatable latch 39 which is held in place on the shaft by a resilient washer 38a mounted in a notch on the end of the shaft. The latch member has a notch di) in one end which cooperates with the semi-circular end portion 33 of shaft 29 in its unarmed position and is engaged by resilient element 40a mounted on frame member 28 when in its armed position. A plate 41 of insulating material is mounted transversely of latch 39 on a projection 39a at the end opposite from notch 4), the plate having openings 41a therein through which extend resilient switch contact members 42 and 43 mounted on the insulating disc 2() by means of rivets or other suitable means. The free ends of resilient members ft2 and 43 are adapted to cooperate with contacts 44 and 45, respectively, carried by insulating disc 20, as will be explained presently.

A fourth shaft de supported by frame member 27 and block 21 carries a gear wheel 47 which meshes with gear wheel 3) and carries pins 48, 49 and Sil cooperating with arms 25 and 26 on the slide. Rotatably mounted on shaft i6v is a sleeve Si carrying contact pin 52 which is adapted to move into contact with conductor 53 mounted on insulating disc 20 when the sleeve is rotated to the proper position, as Will be explained presently. A helical spring 54 is mounted around shaft 46 and sleeve 51 with one of its ends fixed in frame member 27 and its other end attached to gear wheel 47. The spring engages contact pin 52 at a fraction of the distance from frame member 27 to gear wheel 47, this fraction being of the order of one-fifth of the distance. By connecting pin 52 to the spring in this manner, it will be seen that gear wheel 47 is rotated several times for every rotation of sleeve 5l and contact pin 52, the ratio of the number of turns made by the gear wheel to the number of turns made by sleeve 51 being approximately in the ratio which the total spring length bears to the spring length between the end of the spring which is attached to member 27 and the point where the spring is attached to sleeve S1 and pin 52. Thus, several revolutions of the gear d'7 take place while the pin 52 is moving from its starting position lshown in Fig'. 2 to its nal positioncontacting conductor 53.

Gear wheel 47 has approximately 3 times as many teeth as gear wheel 3i) so that a 30 degree'r'otation of the larger wheel will result in a rotation of the smaller gear of approximately 90 degrees in the opposite direction, and vice versa.

A cover disc 56 made either of a plastic substance as indicated, or of metal and having an axial opening S7 is mounted on the upper side of the block 21 by means of screws 58. The disc serves to hold the slide 23 in place and is made of a material suciently thick to assure the safety of the device in case of accidental discharge of the squib in the unarmed position.

In operation, before the projectile carrying the device is iired from the gun, the parts of the device are in the positions shown in Figs. 2 through 7, with slide 23 separating the squib (not shown) in passage 21a from the booster charge (not shown) outside the passage 57. Semi-circular end portion 33 of shaft 29 extends into notch 40 in the latch member 39 to retain latch 39 in its initial position, as shown in Fig. 3, and to prevent shaft 29 with the gears which it carries from rotating in a clockwise direction, as seen in Fig. 3. Switch members 42 and 43 are maintained separated from their respective contacts 44 and 45 by plate 41 and by their own resiliency, so that these circuits are open. With slide 23 in its unarmed initial position, as best seen in Figs. 2 and 5, the conducting strip 24 carried by the slide is separated from resilient switch elements 24b so that the circuit involving these elements is open. Pin 52 in its original position, as shown in Figs. 2, 4 and 6, is separated from its contact 53.

When the projectile containing the device is fired, the device is accelerated in the direction of the arrow in `iEig. l, and the resulting force of setback acting on weight 32 revolves notched wheel 31 clockwise (Fig. l) from the position shown in Fig. 7 to a position in which the weight is in its uppermost location, as viewed in Fig. 1. In order for notched wheel 31 to be so rotated, the force acting on it must be great enough to overcome the force of spring 54- and rotate end portion 33 of shaft 29 out of notch 40. When this occurs, latch 39 is rotated upon continued acceleration, due to its inertia, to the position in which it is shown in Fig. 8, in which the resilient element 40a extends into notch 40 to retain the latch in its armed position. Rotation of latch 39 moves plate 41 toward disc 20, bending resilient switch elements 42 and 43 into engagement with their respective contacts 44 and 45 to complete a battery circuit or other circuit involving these members. By closing these switches rst, electronic tubes which may be involved in the circuit can be heated prior to operation of other parts of the fuze, so as to assure operation of the fuze at the proper time.

As soon as the acceleration of the projectile diminishes to a point where the force of spring 54 is greater than the force of setback tending to maintain the weight 32 in its uppermost position, spring 54 begins to rotate gear 47 in a clockwise direction as viewed in Fig. l, resulting in rotation of gear 30 and notched wheel 31 in the opposite direction. As the gear wheel 47 rotates, pin 50 on the gear wheel is moved downwardly in Fig. and pins 4S and 49 are moved to the left in Fig. 5 into contact with arms 2S and 26, respectively, on slide 23, moving the slide to the left to the armed position in which it is shown in Fig. 9. When the slide is in this iinal or armed position, the tube 23a carried by the slide is aligned with the squib passage 21a and with the booster opening 57 so as to establish an uninterrupted passageway connecting the squib (not shown) and a booster charge (not shown). As conducting strip 24 on the slide 23 moves to the armed position, it strikes resilient contact members 24h and moves past these members to the position shown in Fig. 9 so that the resilient switch members 24b are positioned against shoulder 24e to retain the slide in its armed position. The completion of the circuit across members 24b preferably arms the fuze by connecting the squib into a relay circuit so that the fuze may re the squib.

In rotating gear wheel 47, spring S4 at the same time rotates sleeve 51 on shaft 46 so as to move the contact pin S2 in an arc toward the conductor 53. As explained above, the length of the portion of spring 54 between the end which is xed in frame member 27 and the point where spring 54 is attached to pin 52 bears a xed relation to the total length of the spring, and this relation determines how rapidly sleeve 51 and pin 52 rotate as compared with the rate of rotation of gear wheel 47. Pin 52 and conductor 53 constitute a self-destructive feature of the device, the contact of the pin and conductor ring the squib to detonate the projectile if the fuze has not already done so. By selecting the desired spring portion ratio, as explained above, the self-destruction of the projectile is caused to take place upon the expiration of a desired time interval after the device is armed.

The escapement consisting of pins 36 and 37, oscillating escapement weight 35, and notched wheel 31 on the shaft 29 retards the rotation of gear wheel 47 which meshes with gear wheel 30. This retarding action provides a delay period between the various operations of which the rotation of gear Wheel 47 is a part and prevents arming of the device by minor accelerations.

An important feature of the invention is the provision of means for locking the various elements of the device in their initial and iinal positions. The inter-locking feature, involving end portion 33 of shaft 29 and the notch 40 of latch member 39, maintains all the partsof the device in their initial positions until the force of setback moves wheel 31 suiciently to free portion 33 from the notch 40. When the latch member 39 is rotated by the force of set back to the position in which it is shown in Fig. 8, it is locked in this armed position by means of the resilient member 40a which extends into notch 40. In this way, the latch 39 is held against return to its former position, and switches 42 and 43 are held closed. Pins 49 and 50 prevent movement of the slide from its unarmed to its armed position by engaging arms 25 and 26. Once the slide is moved to its armed position, however, the resilient members 24b by their contact with shoulder 24e on the slide hold the slide in its armed position.

The invention herein described may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

I claim:

1. An inertia-operated arming device for use in an electrically operated projectile fuze having a powder train, comprising in combination, a frame, an inertia element mounted for rotation in said frame in response to a force of setback on sustained acceleration of the device, a locking member rotatable with said inertia element between angularly spaced locking and releasing positions, a latch member pivotally mounted in said frame and having a notch portion engageable by said locking member in its locking position to retain said latch member against movement, a switch operable by said latch member, a helical spring having opposite ends one mounted on the frame and the other acting to oppose the setback actuated rotation of said rotatable element, a switch arm located intermediate the ends of said spring and rotatable upon coiling and uncoiling of said spring, a contact on the frame co-acting with said arm, a slide reciprocally mounted on the frame and normally interrupting said powder train and movable by said helical spring to a noninterrupting position upon a substantial cessation of acceleration, and a switch operable by said slide.

2. An inertia-operated arming device for use in an electrically operated projectile fuze having a powder train, a frame, comprising in combination, an inertia element mounted for rotation in said frame in response to a force of setback on sustained acceleration of the device, a locking member rotatable with said inertia element between angularly spaced locking and releasing positions, a latch pivotally mounted in said frame and having a notch portion normally engaged by said locking member in its locked position to retain said latch against movement, a

switch operated by said latch, said latch being movable by a sustained force of setback to operate said switch upon disposition of said locking member in its releasing position, means for retaining Jthe latch in the position to which it is moved by a sustained force of setback, a gear wheel mounted for rotation in the frame and rotatable with said inertia element, a second gear wheel meshing with said first-named gear wheel and having a pin projecting from one side thereof, a helical spring having opposite ends one mounted on the frame and the other urging said rotatable element and said pin carrying wheel in a direction opposite to the direction of their setback actuated rotation, a switch arm located between the ends of the spring, a self-destruction contact mounted on the frame adapted to coact with said arm, a slide normally interrupting the powder train and having projections engaging said pin whereby said slide is normally retained in its interrupting position and is moved to a noninterrupting position upon rotation of said pin-carrying gear wheel under the influence of said spring, and a switch operated by said slide.

3. In an arming device for use in a projectile fuze having a powder train, a frame, a rotatablemember journaled in the frame and having pins extending 'from one of its faces and moving in circular paths upon rotation of said member, spring means carried by the frame tending to rotate said member, means normally securing said member against its spring actuated rotation and operable upon sustained acceleration of the device to release said member, and a slide reciprocably mounted on the frame normally interrupting the powder train and having arms normally extending across said circular paths for camming coaction with said pins, one of said pins through abutment with one of said arms being adapted to maintain said slide in its normal position until rotation of -said member and another of said pins being adapted upon rotation of said member to move the slide to a noninterrupting position.

4. In an inertia-operated arming device for use in a projectile fuze, a frame, a rotable inertia element journaled in the frame, a locking member rotatable with said inertia element between locking and releasing positions, a pivoted latch having a notched portion adapted to engage said locking member in its locked position to retain said latch against movement, the notched portion of said latch being adapted to abut said member in its released position, said latch and member when actuated by a sustained force of setback on said device being disengagable through initial rotation of said member to its releasing position and subsequent pivotal movement of said latch away from said member, and a switch actuable by said latch.

5. In an electrically operated projectile fuze, a frame, arming means mounted on the frame, a helical spring having opposite relatively twistable ends on connected to the frame and the other to the arming means for actuating said arming means, a rotatable switch contact connected to said spring at a convolution between the ends of said spring and disposed in radially projecting relation to said convolution for rotation upon coiling and uncoiling action ot the spring, and a stationary contact on the frame in the path of rotation of the rotatable contact, whereby said contacts are closed at a predetermined time subsequent to arming of the fuze depending on the position of the attachment of the rotatable contact to the spring.

6. In an electrically operable projectile fuze, a frame, arming means mounted on the frame, a rotatable element for operating said arming means, a helical spring having opposite relatively twistable ends one connected to the frame and the other to said rotatable element for actuating said rotatable element, a switch arm connected to said spring at a convolution between the ends of said spring and disposed in radially projecting relation to said convolution for rotation upon coiling and uncoiling action of the spring, and a stationary contact mounted on the frame in the path of rotation of the switch arm, whereby ti said arm and-said contact engage at a predetermined time subsequent to arming of the fuze depending on the position of the attachment of the rotatable contact to the spring.

7. In an arming device for use in a projectile fuze having a power train, a frame, an element movably mounted on the frame and normally interrupting the powder train, locking means for retaining said element in its unarmed position and operable on sustained acceleration of the device to release said element, a helical coil spring having opposite lrelatively twistable ends connected between the frame and said element and adapted upon untwisting of said spring for moving said element to its armed position, a switch operable by said locking means, an arming switch operable by said interrupting element, and a selfdestruction switch including a movable contact attached tothe spring intermediate its ends for actuation of said switch by said spring subsequent to movement of said element to its armed position.

8. In an arming device, a frame, a switch mounted on the frame, a helical coil spring for closing said switch, governing means to control the rate of closing of said switch, said spring upon coiling and uncoiling acting to drive said governing means, a movable electrical contact member attached to said spring intermediate its ends, and a second contact member mounted on the frame adapted to be struck by said movable contact member.

9. In an arming device, a frame, a switch mounted on the frame, a helical coil spring for closing said switch, governing means to control the rate of closing of said switch, said spring having an end fixed to said device and a movable end rotatable upon twisting and untwisting of said spring to drive said governing means, a movable contact member attached to said spring at a distance from the fixed end of said spring equal to less than half the length of said spring, and a second contact member adapted to be struck by said movable contact member.

10. In an arming device, a frame, a switch mounted on the frame, a spring tor closing said switch, governing means to control the rate of closing of said switch, a shaft rotatably mounted on the frame, said spring surrounding said shaft and acting to drive said governing means, a Sleeve surrounding said shaft, an electrical Contact member fast on the sleeve and connected for rotation therewith by said spring at a location intermediate the ends of s'aid spring, and a second contact member carried by the frame in position to be struck by said sleeve contact member.

ll. In an arming device, a frame, a first electrical contact member mounted for movement relative to the frame, a second electrical contact member mounted on the frame, a spring having ends connected between said frame and first contact member to move said rst Contact member into contact with said second member, and governing means driven by said spring to regulate the rate of movement of said first member, said first contact member being attached to said spring intermediate the ends thereof.

12. In an arming device, a frame, a switch carried by the frame, means for closing said switch, governing means to control the rate of closing of said switch, a shaft journaled in the frame and driving said switch closing means and said governing means, an end of said shaft having a portion of substantially semi-circular cross section, a notched latch pivoted to said device, said semir circular shaft end being adapted to be meshed with said notch mutually to lock said shaft and said latch, and an inertia mass eccentrically associated with said shaft adapted to release said latch responsive to acceleration of said device in a direction transversely of said shaft.

13. The combination in an arming device, a coil spring, means xing the spring at one of its ends, the other end of said spring being twistable relative to said fixed end, an element connected with said spring at a convolution thereof intermediate said ends of said spring, said element projecting outwardly from said convolution and,

upon coiling and uncoiling of said spring, moving with said convolution through a displacement in substantially the same proportion relative to the displacement of said movable end as the number of turns of said spring between the said xed end and said element bears to the total number of turns of said spring.

Ruhlemann Sept. 30, 1930 Woodberry May 24, 1938 Erich Nov. 22, Dawson Ian. 17, Dezzani Oct. 1, Ferrel Sept. 9, Daly July 2, Elmer July 2, Leonard Aug. 27,

FOREIGN PATENTS Italy Dec. 4, Great Britain July 18, 

